Sedimentation velocity is an important hydraulic characteristic and motion parameter, and many scholars have done a lot of work in this field. According to the experimental data, the formula for calculating the settlement velocity of the transitional zone and the three criteria are determined. The comprehensive mathematical model of the velocity of sediment deposition is put forward, and the calculation table is be given for the search. Finally the paper compares the sedimentation velocity of transition zone with several commonly used formulas, and the results show that the proposed method is of high precision.